Apparatus and method for providing transaction services, in particular a computer-based transaction machine, such as an ATM, and a method for providing transaction services using said transaction machine. One or more software applications interact with middleware software through functional interfaces that are hardware independent but provide functionality which is implemented in a manner adapted to the capabilities of the particular hardware implementation. Objects provided for standard transaction functions are independent of the interface between the user and the transaction machine, said interface being customizable. The resulting transaction machines are typically combined into networks and these networks may readily be combined to form an Extranet.